In circular economy of battery scraps, lithium elements in battery scraps are generally recovered by precipitating lithium fluoride with sodium fluoride. The prepared crude lithium fluoride serves as a lithium raw material and then is refined into lithium carbonate. The most serious problems are decomposition and fluoride removal of the lithium fluoride. Conventional acidolysis is relatively difficult, consumes a lot of acid, has a severe operating environment, and has low decomposition rate. It needs repeated decomposition, so that a technological process is long and cost is high. Due to high corrosivity of the hydrofluoric acid produced after decomposition, it is volatile, has high requirements for corrosion prevention of equipment especially in a strong acid environment, and requires enormous investment. It is also very difficult to protect operators. Therefore, there is no better method for preparing lithium carbonate from lithium fluoride at present.